IMO as I am no expert ...if you "can" run comfortably I can't see a problem...but it will make no improvement on your riding either except to sustain a bit of a cardio workout if you are off the bike for a while.
I used to enjoy running but 50 meters will do me in now...but I still get the urge especially after a ride.

runnig is a great cardio work out, and for fitness is better overall than cycling, as you use your core a lot more as well as your arms to some degree. as long as your enjoying i'd say keep up with the running as its only going to benefit you in your cycling and your overall health.

as someone else said earlier unless your going to give the tour de france a go this year every bit of cardio work helps, and will only benefit your aerobic capacity which will hell your cycling if aything

toolonglegs wrote:Cycling is bad for your bones if that is all you do...you need a bit of weight bearing exercise.

I wouldn't worry about that nor would I label it "bad". The bony density induced may be a bit lower than after hours of pounding the tarmac, but it would not be that different to a swimmer. Further, it'll still be higher than a sedentary person who doesn't exercise. Leg/knee muscle imbalance would be a better reason for the cross training.

true...it may be bad for your bones to only do cycling...some weight bearing exercise may be needed for good bone density.
But there is a possiblity that just sitting on your arse is better as you arent depleting your body to such an extent...if is true or not it's your body so look after it....
...which is why hormone replacement may be a good thing even thou it is cheating if you race

thepj wrote:what about boxing/kickboxing, would it affect your cycling?

depends if someone knocks you out or not ...if you are racing then bulking up for boxing isn't of much use.Shite...do what you want...unless you are aiming at being a pro it isn't a big deal.
I took this a while back...but Lovemore is nearly 40 and out of all the boxers I have photographed his physic was amazing!!!.